Numerous hedge funds (assuming they haven't sold their shares) suffered losses when Allergan's stock dropped 16% on Tuesday after scrutiny from the US government over so-called tax-inversion deals, which allow companies to move their headquarters to another country and benefit from a lower tax rate.

In this case Pfizer would have relocated its headquarters to Ireland, where Allergan is based.

Goldman Sachs recently had Allergan ranked No. 1 on its list of stocks that "matter most" to hedge funds. According to Goldman, 80 hedge funds it tracked held Allergan as a top-10 holding.

Here's a rundown of the hedge funds that owned Allergan shares.

(Note:H edge funds have to disclose their long equity holdings every quarter in a 13F form. These filings don't come out until 45 days after the end of each quarter. It's possible that they could have traded in and out of those positions since that time.)

Viking Global (Andreas Halvorsen): 5,987,075 shares

Paulson & Co. (John Paulson): 5,532,600 shares

Third Point (Daniel Loeb): 5,400,000 shares

Pentwater Capital Management: 4,316,368 shares

Elliott Management (Paul Singer): 2,020,500 shares

Blue Ridge Capital (John Griffin): 2,000,000 shares

Sachem Head Capital: 1,685,000 shares

Senator Investment Group: 1,575,000 shares

Farallon Capital Management: 1,275,000 shares

Jana Partners (Barry Rosenstein): 1,164,664 shares

As a group, these 10 hedge funds may have seen $1.33 billion in value wiped off their stakes.

Shares of Allergan fell $41.52, or 14.69%, and closed at $236.03 a share on Tuesday. The stock was last down about 1.27% in the premarket at $233.04 a share.